Method for inhibiting plant growth

ABSTRACT

THIS INVENTION RELATES TO METHODS FOR CONTROLLING AND PROTECTING PLANT LIFE BY THE APPLICATION OF AN N-ARYLSULFONYL CARBAMATE ESTER, OR THE AMINE OR METAL SALT THEREOF.

United States Patent 01 hoe 3,799,760 Patented Mar. 26, 1974 Int. Cl.A01n 9/14 US. Cl. 71-103 13 Claims ABSTRACT OF THE DISCLOSURE Thisinvention relates to methods for controlling and protecting plant lifeby the application of an N-arylsulfonyl carbamate ester, or the amine ormetal salt thereof.

This application is a continuation-in-part of my copending U.S.application, Ser. No. 266,513, filed Mar. 20, 1963, now abandoned, whichin turn was a continuation-inpart of US. application Ser. No. 256,840,filed Feb. 7, 1963, now abandoned. Ser. No. 256,840 was a pendingapplication at the time Ser. No. 266,513 was filed.

This invention relates to methods for controlling and protecting plantlife by the application of N-arylsulfonyl carbamate esters or by theapplication of the amine or metal salts of N-arylsulfonyl carbamateesters. The invention further relates to certain N-arylsulfonylcarbamate esters and their amine and metal salts as novel compositionsof matter.

In recent years, the use of chemicals for controlling various biologicalforms has found widespread acceptance among many people. This isespecially true among agriculturalists interested in controlling plantsystems and insect pests. For example, chemical compositions havepreviously been applied to the soil or to the foliage of fully developedplants, thereby destroying certain types of plants in a selective mannerand allowing others to continue their growth in a more favorableenvironment. This type of control, enabling certain plants to growfreely unhampered by competing noxious plants, has also been achieved bythe application of chemical compositions to the soil, which chemicalcompositions either prevent germination of undesirable seeds or destroythe emerging seedlings immediately after germination. Other dangersconfronting plant growth and crop yields occur in the form of insectpests and plant diseases. These threats to desirable plant life havebeen lessened by the application of insecticides and fungicides to thesoil, foliage of the plants, and surrounding atmosphere.

It is an object of this invention to provide novel methods forinhibiting the growth of plant life. It is a further object of thisinvention to provide certain N-arylsulfonyl carbamate esters as novelcompositions of matter. It is a further object of this invention toprovide certain amines and metal salts of N-arylsulfonyl carbamateesters as novel compositions of matter. It is yet another object of thisinvention to provide methods for both pro-emergence and post-emergencecontrol of undesirable plant life. Additional objects, benefits andadvantages will become apparent as the detailed description of theinvention proceeds.

The compounds useful in the practice of the present invention are thosehaving the molecular configuration:

Q-sm-m-b-om Y where X, Y, and Z are selected from the group consistingof hydrogen, chloro, bromo, iodo, nitro, and lower alkyl; where R isselected from the group consisting of hydrogen, alkyl, cycloalkyl,alkenyl, alkynyl, aryl, alkaryl, aralkyl, and acyl; and where R isselected from the group consisting of alkyl, cycloalkyl, alkenyl,alkynyl, aryl, alkaryl, aralkyl, and acyl.

Compounds of this invention are useful as herbicides.

The herbicidal activity can be demonstrated by contacting a plantstructure with the compound, which may take place either pre-emergentlyor on established plants. Pro-emergence application may be accomplishedin either of two ways-by application of the compounds to the surface ofthe soil or by incorporation of the compounds into the surface layer ofsoil. Depending upon the particular plants to be controlled, thecompounds of this invention may exhibit more activity in one type ofapplication than in another. Post-emergence application is usuallycarried out by contacting the foliage of the plants with the compoundsalthough application to the soil in the vicinity of the plants can alsohave some beneficial effect. Some of the compounds possess activity bothas pro-emergence and post-emergence herbicides. Hence, the user canbenefit from the application of some compounds in a dual mannerdepending upon which compound or mixture of compounds are selected.

The N-(arylsulfonyl) carbamates useful in the practice of this inventionmay contain an unsubstituted benzene ring attached to the sulfonylgroup, as for example, ethyl N-(benzenesulfonyl) carbamate. The presentinvention also encompasses compounds containing substituents on thearomatic ring in either the ortho, meta, or para position. Furthermore,combinations of ortho and meta, ortho and para, meta and para, andortho, meta and para substitutions are within the scope of thisinvention, as well as di-ortho and di-meta combinations. Thesesubstitutions on the ring may consist of halogen atoms, particularlychlorine, of nitro radicals, and of lower alkyl radicals such as methyl,ethyl, propyl, isopropyl, n-butyl, isobutyl, secbutyl, tert-butyl,n-amyl, isomeric amyl, n-hexyl, and isomeric hexyl radicals. Inaddition, mixed substitutions on the aromatic ring such as 3-nitro,4-chloro and 2-rnethyl, 4-chloro provide compounds within the scope ofthis invention. Common and easily prepared substitutions on the aromaticring comprise 2,4; 2,6; and 2,4,6 combinations.

In the series RSO NHCO0C H where R is an aryl radical, generalherbicidal activity was increased with variation of R as follows:

Compounds illustrative of these many possible substitutions include:

ethyl N-(p-toluenesulfonyl) carbamate;

ethyl N-(o-toluenesulfonyl) carbamate;

ethyl N-(2,6-dichlorobenzenesulfonyl) carbamate; ethylN-(2-chloro-p-toluenesulfonyl) carbamate;

ethyl N-(m-nitrobenezenesulfonyl) carbamate;

ethyl N-( 3,4-dichlorobenzenesulfonyl carbamate;

ethyl 'N-(2,4,6-trichlorobenzenesulfonyl) carbamate; and ethylN-(p-cumenesulfonyl) carbamate.

The substituent attached to the nitrogen atom, R in the generic formula,can be either hydrogen or alkyl, cycloalkyl, alkenyl, alkynyl, aryl,alkaryl, aralkyl, or acyl, preferably containing not more than eightcarbon atoms and more preferably not more than four carbon atoms. Theseradicals may be either straightor branch-chained. Examples of suitablecompounds include:

ethyl N(benzenesulfonyl) N-(methyl) carbamate;

ethyl N-(benzenesulfonyl) N-(benzyl) carbamate;

ethyl N-(benzenesulfonyl) N-(n-butyl) carbamate; ethylN-(benzenesulfonyl) N-(isopropyl) carbamate; ethyl N-be'nzenesulufonylN-(p-ethylbenzene) carbamate; ethyl N-(benzenesulfonyl) N-(p-cumene)carbamate; ethyl N-(benzenesulfonyl) N-(allyl) carbamate; and ethylN-(benzenesulfonyl) N-(acetyl) carbamate.

The ester group, R in the generic formula, is capable of variationsimilar to the nitrogen substituent R, insofar as it can be alkyl,cycloalkyl, alkenyl, alkynyl, aryl, alkaryl, aralkyl, or acyl, preferabycontaining not more than eight carbon atoms. These groups may also beeither straightor branch-chained. In the series -somnooon where R=alkly,activity was increased with the following changes'in R:

CH: /CH: CHaH-CH1 CE CHa CHa-CH2 CH: Examples of compounds illustrativeof this variation in-' clude: methyl N-(benzenesulfonyl) carbamate;isopropyl N-(benzenesulfonyl) carbamate; vinyl N-(benzenesulfony)carbamate; allyl N-(benzenesulfonyl) carbamate; tert-butylN-(benzenesulfonyl) carbamate; benzyl N-(benzenesulfonyl) carbamate; andphenyl N -(benzenesulfonyl) carbamate.

N-(arylsulfonyl)carbamates are strongly acidic materials which formstable salts with amines or inorganic bases. These salts are also usefulin various aspects of plant control. Examples of such salts include:ethyl N (benzenesulfonyl) carbamate salt of cyclohexylamine and2'-dimethylaminoethyl-p-nitrobenzenesulfonyl carbamate salt of N,N-dimethylaminoethanol. The alkali metal and alkaline earth metal saltsof the N-(arylsulfonyl) carbamates are also easily prepared by reactingthe subject carbamates with the selected basic material such as NaOH,N21 CO KOH, and Ca(OH) Preferred amine salts are the secondary aminesalts; preferred metal salts are the sodium, calcium and magnesiumsalts. The amine and metal salts are stable, easy to handle, and ingeneral possess a biological toxicity equal to that of the parentcarbamate. In some cases, certain types of biological activity may evenbe enhanced by conversion of the carbamate to the metal or amine salt.

Two general methods were used to prepare N-(arylsulfonyl) carbamates-thereaction of the corresponding sulfonamide with suitable chlorocarbonatein (1) dry acetone in the presence of anhydrous potassium carbonate orin (2) aqueous alkali. The preparation of amine and inorganic salts wasaccomplished by dissolving the 4 N-(arylsulfonyl) carbamate in dry etherand adding a suitable amine also dissolved in ether, or an inorganicbase dissolved in an ether-miscible solvent.

In the preparation of the above-mentioned carbamates by the firstmethod, the reaction proceeded in the follow ing manner:

Aryl-SOzNHz Gl-C R; Aryl-S OzNK- OR;

dry aetone In the first step, a chlorocarbonate is added to a mixture ofa selected arylsulfonamide and powdered anhydrous potassium carbonate indry acetone. Relative quantities of the reactants are not critical, buta good yield of prod not based upon the percent of arylsulfonamideconverted to the carbonate can be achieved by using quantities of thechlorocarbonate and potassium carbonate in excess of the stoichiometricamount. Acetone sufficient to dilute the reactants is used. Thechlorocarbonate should be added slowly over a period of several minuteswith vigorous stirring to prevent re-precipitation of the sulfonamide.After addition, the mixture is heated to reflux temperature and held atthis temperature for an hour or more. I have found 5-6 hours to besufiicient for most of my experimentation, but a shorter or longer timemay be desirable, depending upon the reactants and the percent yielddesired. After cooling, the slurry formed by the reaction is allowed tostand at room temperature for a period of time, overnight if convenient.Upon standing, a white solid is formed which can be collected on afilter and washed with acetone. This solid material is then dissolved inWater, and the solution may be filtered and extracted with ether. In thesecond step of the preparation, the solution should be cooled to atemperature 'which Will permit a satisfactory rate of reaction--coolingto 0 C. in an ice bath is suggestedand treated with an excess ofconcentrated mineral acid to liberate the crude product. The product atthis point may be extracted with a suitable water-immiscible solventsuch as ethyl ether or benzene. The solvent and extracted product arethen dried over a dessicant such as CaSO, or MgSO and the solventsubsequently removed under reduced pressure. If a highlypurified-product is required, the product may be recrystallized from asuitable solvent.

in the preparation of N-(arylsulfonyl) carbamates in an aqueous alkalimedium, the reaction proceeds in the 1 following manner:

In the first step of the preparation, a selected sulfonamide isdissolved in an aqueous solution containing a quantity of an alkalimetal base such as NaOH or KOH slightly in excess of the amountnecessary for complete reaction with the sulfonamide. The solution isthen filtered to remove reprecipitated sulfonamide and cooled to around15 C. A chlorocarbonate and a 10% aqueous solution of an alkali metalbase are then added slowly with stirring, the rate of addition beingadjusted so that no precipitate is formed. Stirring at room temperaturefor several hours is recommended; overnight stirring is satisfactory.The solution is filtered to remove any solids, and the filtrate thencooled to 10 or 15 C. and acidified with dilute (520%) HCl to a slightlyalkaline condition.

Stirring for several minutes to allow complete reaction is desirable.Any solid formed in this step is filtered off and the filtrate furtheracidified to a slightly acid condition. Again any formed solid isfiltered 01f and filtrate cooled to 5-10 C. Further acidification to pH1 or 2 is eifected with concentrated (12 M) HCl. Stirring for around twohours at 510 C. is suggested to insure a maximum yield of product. Thewhite solid may then be filtered, washed with water, dried in air, andrecrystallized from a suitable solvent such as ethyl ether.

The advantages and benefits of the present invention will become morefully understood when interpreted in view of the detailed descriptionset forth in the following examples.

EXAMPLE -I A quantity of 51.5 grams (0.30 mole) of p-toluenesulfonamidewas added to 132 grams of NaOH (0.30 mole) diluted with 100 ml. ofwater. Nearly complete solution was achieved. The solution was cooled to16 C. A small portion of the 32.5 grams (0.30 mole) quantity of ethylchlorocarbonate was added to the solution, causing the formation of asmall amount of precipitate. To prevent the formation of precipitate,10% NaOH was added as required. The remainder of the ethylchlorocarbonatewas added slowly over a period of 90 minutes. Thesolution was stirred for six hours as 10% NaOH was added to maintainsolution of the components. The temperature of the solution wasmaintained between 16 and 19 C. throughout this part of the experiment.At the end of the six hour stirring period, the solution was allowed tostand overnight at room temperature. The total amount of 10% NaOH addedwas 375 grams. After standing, the solution was filtered to remove 2.5grams of solid material. The filtrate was partially acidified by slowaddition of dilute HCl (15.4 grams of concentrated 12 M HCl diluted to50 ml. with water). A quantity of 19.8 grams of solid material formedwhich was removed by filtration. The filtrate was then treated with moredilute HCl to bring the pH down to around pH 8. This caused theformation of 1.2 grams of solid which was removed by filtration. To thisfiltrate, 30.8 grams of concentrated HCl was added slowly with stirring.A white precipitate formed around pH 5 with ml. of acid still to beadded. After the acid was added, the pH was 3.5 and a white oil hadseparated from the solution. This oil solidified on cooling to roomtemperature. The filtered precipitate was washed with water and dried inair. This material was ethyl N-(p-toluenesulfonyl) carbamate. Weight ofthe material was 30.1 grams which represented a 41.2% yield. Softeningpoint was 75 C.; melting point was 79- 81 C. After a crystallizationfrom a benzene-hexane solvent, the softening and melting points wereunchanged. The prepared compound was identified as ethyl n-(ptoluenesulfonyl) carbamate.

EXAMPLE II A quantity of 42.7 grams (0.20 mole) ofN-n-butylbenzenesulfonamide was dissolved in 100 grams (1.0 mole) oftriethylamine. To this solution 28 grams (0.26 mole) of ethylchloroformate was added slowly with stirring over a 70 minute period.The solution was cooled as necessary to maintain the temperature around20 C. During the addition of the chloroformate, a pink slurry was formedand there was also a noticeable evolution of gas. After addition of thechloroformate, stirring was discontinued but the reaction mixture wasallowed to remain in the cooling bath at 20 C. for an additional 2.5hours. After standing overnight at room temperature, the mixture wasfiltered and 23.5 grams of pink solid material was removed from themixture. Excess solvent was removed from the filtrate by evaporation at65 C. and 9 mm. pressure. An orange oily residue remained which wascooled to 20 C., stirred, and treated with 50 ml. 10% NaOH. About 100m1. of ether was added and the mixture stirred for an additional 10minutes. When the stirring was stopped, the ether layer was separatedfrom the aqueous layer, washed successively with Water, 10% HCl, water,and saturated NaCl solution, and then dried over MgSO Solvent wasevaporated at 70 C. and 14 mm. pressure. The prepared compound wasidentified as ethyl N(benzenesulfonyl) N-(n-butyl) carbamate. Weight ofthe product was 48.5 grams which represented a yield of 85.2%; n 1.5064.Treatment with HCl was unnecessary since a carbamate such as this withno available hydrogen attached to the nitrogen does not form a saltrequiring neutralization to form the desired product. The 10% HCl washused above was used only to remove entrained NaOH or K CO EXAMPLE III Aquantity of 50 grams (0.29 mole) of o-toluenesulfonamide was dissolvedin 140 grams of 10% NaOH. This mixture was diluted with ml. of water toobtain a nearly complete solution. The solution was cooled to 15 C.Ethyl chlorocarb-onate (33 g., 0.30 mole) was added slowly with stirringalong with sufficient 10% NaOH to maintain solution of the sulfonamide.After the chlorocarbonate was added, the solution was stirred at thisreduced temperature for approximately an hour. The solution was allowedto stand overnight at room temperature. Total NaOH used was 38.1 grams(0.96 mole). The solution was filtered to remove 13.7 grams of solidmaterial. Dilute HCl (17.5 grams of 12. M =HC1 diluted to 50 ml. withwater) was added to the filtrate with stirring. Solid precipitated bythis addition (19.1 grams) was removed by filtration and another 50 ml.quantity of dilute HCl was added to the filtrate. No precipitate wasformed. An additional 35 grams of concentrated HCl was added and a whiteprecipitate formed which was filtered, washed with water, and dried. Theproduct was identified as ethyl N-(o-toluenesulfonyl) carbamate. Weightof product was 17.5 grams which represented a yield of 24.5%. Softeningpoint was C.; melting point was 117-119 C.

EXAMPLE IV Ethyl N- (p-chlorobenzenesulfonyl) carbamate was prepared byreacting p-chlorobenzenesulfonamide (29 grams, 0.15 mole) with ethylchlorocarbonate (21 grams, 0.19 mole) in the presence of 10% aqueousNaOH according to the procedure described in Example III. Weight of thefinal product was 13.4 grams, which represented a yield of 34%.Softening point was 86 C.; melting point was 89-9l C. Uponrecrystallization from a benzenehexane solvent, the softening point was90 C.; melting point was 92-93 C. Calculated nitrogen content was 5.31%,found 5.61%.

EXAMPLE V Ethyl N-(p-nitrobenzenesulfonyl) carbamate was prepared byreacting p-nitrobenzenesulfonamide (30.2 grams, 0.15 mole) with ethylchlorocarbonate (21 grams, 0.19 mole) inthe presence of 10% aqueous NaOHaccording to the procedure described in Example HI. Weight of the finalproduct was 25.8 grams, which represented a yield of 62.8%. Meltingpoint was 132 C.

EXAMPLE VI A quantity of 49 grams of p-toluenesulfonamide (0.29 mole)was added to a slurry consisting of 56.5 grams (0.41 mole) of anhydrousK CO in 500 ml. of dry acetone. Ethyl chlorocarbonate (42 grams, 0.30mole) was added slowly with stirring. This mixture was refluxed for fivehours and allowed to stand overnight at room temperature. A white solidwhich had formed was removed and the acetone filtrate was evaporatedleaving a tan gummy solid. The white solid was dissolved in 750 ml.water and cooled in ice. The solution was acidified to pH 2 with 40 m1.concentrated HCl to precipitate a white oil. This mixture was extractedthree times with 50 ml. portions of ether. Upon evaporation of theether, a hard white solid remained. This solid was identified as ethylN- (p-toluenesulfonyl) carbamate. Weight of the product was 58 gramswhich represented an 82.3% yield. Melting point was 81-83 C. Thisproduct is identical with the product of Example 1. However the yield inthis example was far superior. Biological properties were the same.

EXAMPLE VII A quantity of 20 grams (0.071 mole) of N-benzylp-chlorobenzenesulfonamide was added to a slurry of 18.8 grams (0.136mole) of anhydrous K CO in 210 ml. of acetone. 2-chloroethylchlorocarbonate (18.7 grams, 0.131 mole) was added slowly with stirring.The mixture was refluxed for five hours and then allowed to standovernight. A white solid which formed was removed by filtration. Theacetone filtrate was evaporated, leaving a gummy white residue. Thisresidue was dissolved in 200 ml. ether and extracted twice with 40 ml.portions of NaOH and once with 100 ml. water. The filtrate wasevaporated to leave a white solid. It was unnecessary to react theacetone filtrate With HCl since a carbamate such as this with noavailable hydrogen attached to the nitrogen does not form a saltrequiring neutralization. The white solid left after evaporation of theether is the product 2-chloroethyl N-(p-chlorobenzenesulfonyl) N-benzylcarbamate. Weight of the product was 27.5 grams which represented a 100%yield. Calculated analysis of this compound was C, 49.49%; H, 3.87%; N,3.51%. Found: C, 49.47%; H, 4.01%; N, 3.58%. Sintering point was 128 C.;melting point was 129-130 C.

EXAMPLE VIII A quantity of 22.6 grams (0.10 mole) of3,4-dichlorobenzenesulfonamide was added to a slurry of grams K CO in150 ml. of dry acetone. Allyl chlorocarbonate (12.5 grams, 0.105 mole)was added slowly with stirring. This mixture was refluxed for five hoursand then allowed to stand overnight at room temperature. The solutionwas filtered to remove 11.5 grams of solid material. The acetone solventwas evaporated from the filtrate, leaving behind a yellow gummy residue.This residue was treated with 10 grams NaHCO in 100 ml. water to form awhite solid, which was filtered and dried. The bicarbonate extract wasextracted with 50 ml. ether and the separated aqueous layer wasacidified to pH 2 with concentrated HCl. A gummy white material formed.This mixture was extracted twice with 50 ml. ether. The ether extractwas heated to remove ether, leaving a white solid. This product wasidentified as allyl N-(3,4-dichlorobenzenesulfonyl) carbamate. Weight ofthe product was 5.7 grams which represented a 19% yield. Sintering pointwas 83 C.; melting point was 85-87" C. Product was very soluble inbenzene, acetone, and ether; it was insoluble in water and hexane. Uponrecrystallization from benzene-hexane, the melting point and solubilitycharacteristics were unchanged.

EXAMPLE IX Allyl N-(m-nitrobenzenesulfonyl) carbamate was prepared byreacting 20.2 grams (0.10 mole) of m-nitrobenzenesulfonamide with 12grams (0.10 mole) of allyl chlorocarbonate inthe presence of anhydrous KCO in acetone according to the procedure described in Example VI. Theproduct was a pale yellow oil which solidified on cooling. Weight of thefinal product was 5 grams which represented a yield of 17.8%. Meltingpoint was 8486 C.

EXAMPLE X Allyl N-(p-chlorobenzenesulfonyl) carbamate was prepared byreacting 19.1 grams (0.10 mole) of p-chlorobenzenesulfonamide with 12.5grams (0.105 mole) of allyl chlorocarbonate in the presence of anhydrousK CO in acetone according to the procedure described in Example VI.Weight of the final product was 16 grams, which represented a 58.3%yield. The product was a white gummy solid. Upon recrystallization froma CHC1 -hexane solvent, the yield was 11.2 grams for a 41% yield.Melting point was 63-65 C.

EXAMPLE XI Allyl N-(p-toluenesulfonyl) carbamate was prepared byreacting 51.5 grams (0.30 mole) of p-toluenesulfonamide with 37 grams(0.30 mole) of allyl chlorocarbonate in the presence of anhydrous K COin acetone to the procedure described in Example VI. Weight of the whitesolid product was 40 grams, which represented a 57.5% yield. Sinteringpoint was 63 C.; melting point was 67- 69 C.

EXAMPLE XII Isopropyl N-(p-toluenesulfonyl) carbamate was prepared byreacting 13.5 grams (0.08 mole) of p-toluenesulfonamide with 16.0 grams(0.131 mole) of isopropyl chlorocarbonate in the presence of 18.8 grams(0.136 mole) of anhydrous K CO and 200 ml. of dry acetone according tothe procedure described in Example VI.

The product was a hard white solid, weighing 17.9 grams which representsa yield of 86.8%. Sintering point was 77 C.; melting point was 78-80 C.

EXAMPLE XIII Isopropyl N-(p-chlorobenzenesulfonyl) carbamate wasprepared by reacting 15.4 grams (0.08 mole) ofp-chlorobenzenesulfonamide with 16.0 grams (0.131 mole) of isopropylchloroformate in the presence of 18.8 grams (0.136 mole) of anhydrous KCO and 200 ml. of dry acetone according to the procedure described inExample VI. The product was a hard white solid, weighing 18.6 gramswhich represents a yield of 83.8%. Sintering point was 87 C.; meltingpoint was 89-91 C.

EXAMPLE XIV Isopropyl N-(p-chlorobenzenesulfonyl) N-benzyl carbamate wasprepared by reacting 20.0 grams (0.071 mole) of N-benzylp-chlorobenzenesulfonamide with 16.0 grams (0.131 mole) of isopropylchlorocarbonate in the presence of 18.8 grams (0.136 mole) of anhydrousK CO and 210 ml. dry acetone. After refluxing for six hours and standingovernight, the mixture was filtered to remove a white precipitate. Thefiltrate was evaporated to leave a gummy white solid. This residue wasdissolved in 125 ml. warm isopropanol and the resulting solution addedto 160 grams of 5% NaOH. The white solid which was filtered, washed withwater, and dried. This solid was the carbamate product. Weight was 4.5grams which represented a yield of 17.3%. Sintering point was 78 C.;melting point was -81 C. Calculated analysis was C 55.22%, H 4.92%, andN 3.81%; found by analysis was C 55.34%, H 4.92%, and N 3.69%.

EXAMPLE XV Isopropyl N-(p-toluenesulfonyl) N-methyl carbamate wasprepared by reacting 13.2 grams (0.071 mole) of N-methylp-toluenesulfonamide with 16.0 grams (0.131 mole) of isopropylchlorocarbonate in the presence of 18.8 grams (0.136 mole) of anhydrousK CO and 200 ml. dry acetone according to the procedure described inExample XIV except that the solid from the acetone filtrate wasdissolved in 100 ml. ether instead of isopropanol. The ether extract wasthen heated under 'vacuum to remove the ether and leave a clearcolorless oil which solidified on cooling. This solid was the carbamateproduct. Weight of the product was 11.4 grams which represented a yieldof 60%. The product was recrystallized from a water-alcohol solvent (10ml. water+35 ml. alcohol/5% water). Sintering point was 65 C.; meltingpoint was 7072 C- ject carbamates upon selected plant systems at variousrates of application in a pre-emergent application to the soil whereinseeds of these plants are present. The

Roman numerals represent selected N-(arylsulfonyl) carbamates where:

I==Ethyl N-(p-nitrobenzenesulfonyl) carbamate;

fII =Ethyl N-(p-chlorobenzenesulfonyl) carbamate;

III=Ethyl N-(n-butyl) N-(benzenesulfonyl) carbamate;

IV=Allyl N-(m-nitrobenzenesulfonyl) carbamate;

=Allyl N-(p-toluenesulfonyl) carbamate;

VI=Allyl N-(p-chlorobenzenesulfonyl) carbamate;

VII=A1lyl N-(3,4-dichlorobenzenesulfonyl) carbamate;

VIII=Methyl N- (benzenesulfonyl) carbamate;

IX=Isopropyl N-(p-toluenesulfonyl) carbamate;

X=Isopropyl N-methyl-N-(p-toluenesulfonyl) carbamate;

XI ='Isopropyl N-benzyl-N-(p-toluenesulfonyl) carbamate;

XII=Isopropyl N-(p-chlorobenzenesulfonyl) carbamate;

and

XII =Dimethylamine salt of ethyl (p-nitrobenzenesulfonyl) carbamate.

The plants on which the above carbamates were tested are designated inTable I as follows:

A=grass I=foxtail B=broadleaf J=crab grass C=morning glory K=pigweedD=wild oat L=soybean =brome grass M=wild buckwheat F=rye grass N=tomatoG=radish Q=sorghum H=sugar beet The testing procedure used in theevaluation of preemergence activity is as follows. A good grade oftopsoil was placed in either 9 /2" x 5%" x 2%" or 9" x 13 x 2" aluminumpans and compacted to a depth of inch from the top of the pan. On top ofthe soil were placed a designated number of seeds of radish, morningglory, tomato, sugar beet, sorghum, brome grass, wild buckwheat, giantfoxtail, rye grass, wild oat, pigweed, crab grass, and soybean. Twodifferent chemical applications were made; one wherein the herbicidalcomposition was applied to the surface of the soil and the other whereinthe composition was admixed with or incorporated in the top layer ofsoil. For the surface application, the seeds were then covered with inchof prepared soil mixture and the pan leveled. In the soil-incorporationplantings, a weighed amount of prepared soil mixture was blended withthe herbicide composition in a separate mixing container, and this blendwas then used to cover the seeds. The surface application of theherbicide composition was made by spraying the surface of the soil witha solvent solution containing a sufiicient quantity of the subjectcarbamate to obtain the desired rate per acre on the soil surface. Thewatering of the seeds in both type plantings was accomplished by placingthe aluminum pans in a sand bench bringing the water level to /2 inchdepth of water thereon and permitting the soil in the pans to absorbmoisture through the perforated bottoms of the pans and the excess waterto drain through an opening in the bottom of the bench.

The planted pans were maintained there for 14 days under ordinaryconditions of sunlight and watering. At the end of this time, the plantswere observed and the results recorded by counting the number of plantsof each species which germinated and grew. The herbicidal rating wasobtained by means of a fixed scale based on the average 10 percentgermination of each seed lot. Herbicidal activity is indicated accordingto the following scale: O=no phytotoxicity 1=slight phytotoxicity2=moderate phytotoxicity 3=severe phytotoxicity TABLE I A B C D E F G HI I K L M N O II 25 2 0 3 1 1 2 3 3 2 2 3 0 3 2 3 5 0 0 0 0 3 0 0 O 0 00 0 3 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 III-.... 25 1 0 0 0 1 1 0 0 33 3 0 0 0 2 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 '5 0 2 3 0 0 0 0 1 0 1 3 0 02 1 V 5 0 1 0 0 0 0 2 3 0 0 2 0 0 0 0 VI 25 2 2 1 0 0 1 2 2 2 3 3 0 3 33 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 VII--- 25 2 2 0 0 0 2 3 3 3 3 3 0 2 03 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 VIII.... 25 3 2 0 3 3 2 3 3--. 3 3 0 33 1 5 3 2 1 3 3 1 3 3 1 3 3 1 2 3 1 '1 1 0 1 2 1 0 1 1 0 2 1 1 0 1 1XIL-.- 25 2 3 2 1 2 2 3 3 3 2 3 1 1 3 2 10 1 2 0 0 0 0 3 3 3 1 3 1 0 1 1'5 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 XIII 25 3 1 0 3 3 2 3 2 3 3 3 0 0 0 3"5 3 0 0 0 3 3 3 0 3 3 2 0 0 0 3 1 0 0 0 0 1 0 3 0 1 2 0 0 0 0 0 LbSJa.

Incorporation into top soil; treatments not marked with an asterisk aresurface applications.

EXAMPLE XVII In this example, the contact herbicidal activity of thesame N-(arylsulfonyl) carbamates was determined in greenhouse tests. Thecarbamate to be tested was applied in spray form to 21-day old specimensof the same grasses and broadleaf plants as used in the pre-emergencetests described in Example XVI. The same number of seeds of the sameplants used in Example XVI were planted in the 9 /2" x 5% x 2%" aluminumpans arranged in the same manner with a soybean seed in diagonalcorners. After the plants were 21 days old, they were sprayed with sixml. of a 0.5% solution of the subject carbamate which corresponds to arate of approximately 9 lbs. per acre. Ethyl N-(n-butyl)N-(benzenesulfonyl) carbamate and allyl N- (p-toluenesulfonyl) carbamateshowed no contact herbicidal activity. Slight contact herbicidalactivity was shown by ethyl N-(p-nitrobenzenesulfonyl) carbamate, ethylN-(p-chlorobenzenesulfonyl) carbamate, allyl N- (m-nitrobenzenesulfonyl)carbamate, and allyl N-(p-chlorobenzenesulfonyl) carbamate. Moderatecontact herbicidal activity was exhibited by allylN-(3,4dichlorobenzenesulfonyl) carbamate. Good contact herbicidalactivity at 0.2% was shown by the dimethylamine salt of ethylN-(p-nitrobenzenesulfonyl) carbamate.

The herbicidally active compounds of this invention are either solid orliquid materials, depending upon the particular substituents present inthe compounds. To aid in achieving a uniform distribution of the activecompounds over the entire area of the soil or plants to be treated, itis often advantageous to employ a composition comprising a diluent orextending agent in addition to the active compounds. Suitable solidextending agents are 1 1 those which render the compositions permanentlydry and free flowing. Therefore hygroscopic materials are not preferredextending agents unless there is included in the composition a separatesubstance to aid flowability. Effective solid diluents include naturalclays, such as china clays, bentonites, and the attapulgites; otherminerals in their natural state such as talc, pyrophylite, quartz,diatomaceous earth, fullers earth, chalk, rock phosphate, and sulfur;and chemically modified minerals, such as acidwashed bentonite,precipitated calcium phosphate, precipitated calcium carbonate, andcolloidal silica. These diluents may represent a substantial portion,e.g. 50 to 98 percent by weight of the entire formulation as applied toplant or soil. Formulations more concentrated with respect to the activeingredient may be prepared, but they will usually require additionaldilution by the user in order to properly prepare the composition forthe most effective usage. Therefore the toxicant formulation as appliedin the field will normally consist of a minor amount, i.e. less than 50%by weight of the entire formulation, of the N-(arylsulfonyl) carbamateand a major amount, or more than 50% of the entire formulation, of anadjuvant or adjuvants.

Liquid extending agents are also useful in the practice of thisinvention. The N-(arylsulfonyl) carbamates of this invention areinsoluble in water and are readily soluble in most organic solvents.Therefore the choice of a liquid extending agent is quite variable if asolution of the active ingredients is desired. In addition the activecompounds need not be dissolved but merely dispersed in the extendingagent in the form of a suspension or emulsion. One method of formingthis dispersion is to dissolve the N-(arylsulfonyl) carbamate in asuitable organic solvent and then add this solution to water or someother liquid extending agent to form the dispersion. Examples of someorganic solvents suitable for use as extending agents when a solution isdesired include: ethers such as ethyl ether, isopropylether, n-propylether; alcohols such as ethyl, isopropyl, n-propyl, and butyl alcohols;ketones such as acetone, methylethyl ketone, and cyclohexanone; aromatichydrocarbons such as benzene, toluene, xylene and cumene. Solventsuseful as extending agents when a dispersion of the active compound inthe solvent is acceptable include: water, hexane, and other aliphatichydrocarbons.

The incorporation of a surface active agent into the herbicidalformulation is an aid helpful in forming uniform dispersions oremulsions of the active N-(arylsulfonyl) carbamates in water. Thissurface active agent, that is the wetting, emulsifying, or dispersionagent, may be either anionic, cationic, non-ionic, or mixtures thereof.Suitable wetting agents are the organic compounds capable of loweringthe surface tension of water and include the conventional soaps such asthe water-soluble salts of long-chain carboxylic acids; the amino soapssuch as the amine salts of long-chain carboxylic acids; the sulfonatedanimal, vegetable, and mineral oils; quaternary salts of high molecularWeight acids; rosin soaps such as salts of abietic acid; sulfuric acidsalts of high molecular weight organic compounds; algin soaps; andsimple and polymeric compositions having both hydrophilic andhydrophobic functions.

Concentrated compositions of the N-arylsulfonyl carbamates ordinarilyhave the active ingredient and the surface active agent present inhigher concentrations than the toxicant compositions applied in thefield so that upon dilution with an extending agent, compositionscontaining optimum proportions of active ingredient and surface activeagent are prepared to obtain uniform distribution and to maintain theactive ingredient in a form enabling prompt assimilation by the plants.

The concentrate compositions preferably comprise 5% to 95% by weight ofthe active ingredient, the remainder consisting of the adjuvant. If aliquid concentrate is desired, this adjuvant may be solely liquidextending agent or surface active agent, but preferably is a combinationof the two. Preferably the surface active agent comprises from 0.1% to15% of the concentrate, and the liquid extender comprises from 5% to ofthe concentrate. If a solid concentrate is desired, the adjuvant isusually made up solely of a solid extender unless the dust concentrateis to be applied as a wettable powder, in which case an amount ofsurface active agent comparable to that used in the liquid formulation,that is 0.1% to 15%, may be desirable.

Carrier materials or diluents necessary to dilute the concentrates to atoxicological level suitable for plant control may be either a liquid orparticulate solid. Materials mentioned previously as extenders may alsobe used as carriers; however the use of some of these materials ascarriers is often not economically feasible. Water is a preferred liquidcarrier; suitable solid carriers include solid fertilizers such asammonium nitrate, urea, and superphosphate, as well as other materialsin which plant organisms may take root and grow such as compost, manure,humus, and sand.

In addition to the above described conditioning agents, other adjuvantsmay be added, such as insecticides, fungicides, nematocides and otherherbicides of a supplementary nature. This may be done when it isdesired to broaden the spectrum of activity to include problem weeds,insects, or fungi.

The herbicidal compositions containing the N-arylsulfonyl carbamates areapplied to the plant systems in the conventional manner. Thus, the dustand liquid compositions may be applied to the foliage of growing plantsor to the soil by the use of power-operated dusters and sprayers as wellas manually operated devices. Some of the compounds of this inventionprovide superior protection and control when mixed with the top fewinches of soil. This can be accomplished by addition of the compositionto irrigation water supplied to the field to be treated. Dustcompositions sprinkled on the surface of the soil can be distributedbelow the surface by the usual discing, dragging, or mixing operations.

The application of a herbicidally effective amount of theN-(arylsulfonyl) carbamate to the area to be controlled is essential tothe practice of this invention. The exact dosage to be applied isdependent not only upon the specific carbamate but also upon theparticular type of protection desired. As a general rule, thepro-emergence herbicidal activity of the N-(arylsulfonyl) carbamates isthe most significant although the post-emergence activity is quitepronounced for some compounds. Herbicidal activity is usually achievedby application of the N-(arylsulfonyl) carbamates at a rate of fromabout 1 to about 50 pounds per acre. However lower rates of applicationmay be re.- quired with some of the carbamates, particularly if aherbicidally selective activity is desired.

The herbicidally active compounds of this invention have been describedin terms of specific groups or types of N-(arylsulfonyl) carbamates.However it should be noted that this invention is intended to coverthose compounds in which the substituent groups (the X, Y, Z, R, and Rradicals) can also contain constituents other than those mentioned ifthese constituents do not interfere with the biological activity of theparent N-(arylsulfonyl) carbamate. Those skilled in the art willrecognize that a compound containing a hydrocarbon radical that issubstituted with a non-interfering group is the equivalent of thecorresponding compound containing a non-substituted hydrocarbon radical.Such a non-interfering group can be initially present in a compoundsubjected to one of the reactions of this invention and can, dependingon circumstances, either be retained in the product molecule or bedestroyed or changed during the reaction; or such group can beintroduced by known means into one of the new compounds of thisinvention subsequent to the formation of such compound. Accordingly,these and other modifications are contemplated which can be made withoutdeparting horn the spirit of the described invention.

What is claimed is: 1. A method for inhibiting plant growth comprisingapplying a phytotoxic amount of a compound of the formula where X, Y andZ are selected from the group consisting of hydrogen, chloro, bromo,iodo, nitro, and lower alkyl, where R is selected from the groupconsisting of hydrogen, alkyl, alkenyl, aryl, alkaryl and aralkyl havingup to eight carbon atoms, and where R is selected from the groupconsisting of alkyl, alkenyl, aryl, alkaryl and aralkyl having up toeight carbon atoms.

2. A method for inhibiting plant growth comprising ap plying aphytotoxic amount of an alkyl N-arylsulfonyl carbamate wherein saidalkyl has up to eight carbon atoms.

3. A method for inhibiting plant growth comprising applying a phytotoxicamount of an alkenyl N-arylsulfonyl carbamate wherein said alkenyl hasup to eight carbon atoms.

4. A method for preventing undesirable plant growth which comprisesapplying to soils normally supporting said growth a growth-inhibitingamount of a compound of the formula I SO2-N-COOR1 X Z Y wherein X, Y,and Z are selectedfrom the group consisting of hydrogen, chloro, bromo,iodo, nitro, and lower alkyl; where R is selected from the groupconsisting of hydrogen, alkyl, alkenyl, aryl, alkaryl and aralkyl havingup to eight carbon atoms; and where R is selected from the groupconsisting of alkyl, alkenyl, aryl, alkaryl and aralkyl having up toeight carbon atoms.

5. A method for preventing undesirable plant growth which comprisesapplying to soils normally supporting said growth a growth-inhibitingamount of a compound of the formula Q-SO -N-C OR; x

wherein X and Y are selected from the group consisting of hydrogen,chloro, bromo, nitro, and alkyl having up to four carbon atoms; where Ris selected from the group consisting of hydrogen, alkyl, aryl, aralkyland alkaryl having up to 8 carbon atoms; and where R is selected fromthe group consisting of alkyl and alkenyl having up to four carbonatoms.

6. A method for preventing undesirable plant growth which comprisesapplying to soils normally supporting said growth a growth-inhibitingamount of an alkyl N- arylsulfonyl carbamate wherein said alkyl has upto eight carbon atoms.

7. A method for preventing undesirable plant growth which comprisesapplying to soils normally supporting 'said growth a growth-inhibitingamount of an alkenyl N- arylsulfonyl carbamate wherein said alkenyl hasup to eight carbon atoms.

8. A method for preventing undesirable plant growth which comprisesapplying to soils normally supporting said growth a growth-inhibitingamount of a compound selected from the group consisting of: allylN-(p-toluenesulfonyl) carbamate; allyl N-(m-nitrobenzenesulfonyl)carbamate; allyl N (p-chlorobenzene-sulfonyl)carbamate; allylN-(3,4-dichlorobenzene sulfonyl) carbamate; ethylN-(p-nitrobenzenesulfonyl) carbamate; ethyl N-(p-chlorobenzenesulfonyl)carbamate; ethyl N-(benzenesulfonyl) N-(n-butyl) carbamate; and methylN-benzenesulfonyl carbamate.

9. A method for inhibiting plant growth comprising ap plying to saidplant growth a phytotoxic amount of a compound of the formula wherein X,Y, and Z are selected from the group consisting of hydrogen, chloro,bromo, iodo, nitro, and lower alkyl; where R is selected from the groupconsisting of hydrogen, alkyl, alkenyl, aryl, alkaryl and aralkyl havingup to eight carbon atoms; and where R; is selected from the groupconsisting of alkyl, alkenyl, aryl, alkaryl and aralkyl having up toeight carbon atoms. 1

10. A method for inhibiting plant growth comprising applying aphytotoxic amount of an amine salt, alkali metal salt or alkaline earthmetal salt of a compound of the formula wherein X, Y, and Z are selectedfrom the group consisting of hydrogen, chloro, bromo, iodo, nitro, andlower alkyl; where R is selected from the group consisting of hydrogen,alkyl, alkenyl, aryl, alkaryl and aralkyl having up to eight carbonatoms and where R is selected from the group consisting of alkyl,alkenyl, aryl, alkaryl and aralkyl having up to eight carbon atoms.

11. A method according to claim 10 wherein said salt is applied toexisting plant growth.

12. A method according to claim 10 wherein said salt is applied to soilsnormally supporting said plant growth.

13. A method for the selective control of undesirable plant growthcomprising applying to an area to be protected from such growth aherbicidally efiective amount of a compound of the formula:

NOQ-SOzNHCOOCaHI References Cited UNITED STATES PATENTS 3,039,863 6/1962Fancher et al. 71-2.6 3,159,666 12/1964 Heininger et a1. 7l-2.3 X

FOREIGN PATENTS 1,340,297 9/1963 France 712.6

JAMES O. THOMAS, JR., Primary Examiner U.S. Cl. X.R..

